Calcium carbonate, the main component of lime, has been widely used in industry due to its stability and economy. Calcium carbonate has three types of crystalline polymorphism, calcite, aragonite and vaterite, each wi...Calcium carbonate, the main component of lime, has been widely used in industry due to its stability and economy. Calcium carbonate has three types of crystalline polymorphism, calcite, aragonite and vaterite, each with different properties. Therefore, the control of crystal polymorphism is required for industrial applications. In addition, the control of crystal size and shape is similarly required for different applications. In this study, the effect of SrCO<sub>3</sub> on the size control of fine aragonite-type calcium carbonate crystals by uniform urea precipitation and the effect of SrCO<sub>3</sub> addition was investigated by adding solid strontium carbonate and dissolved strontium carbonate. The addition of solid strontium carbonate affected the crystal polymorphism and size of the calcium carbonate produced, depending on the properties of the solid particles and the amount of SrCO<sub>3</sub> added. Experiments on the addition of dissolved SrCO<sub>3</sub> showed that the supersaturation formation rate could be controlled to control the crystal polymorphism.展开更多
Submicrometer-sized, spherical vaterite particles were synthesized by solid-state reaction at room temperature in the presence of poly(acrylic acid)(PAA). The obtained products were characterized by XRD, IR and SEM. I...Submicrometer-sized, spherical vaterite particles were synthesized by solid-state reaction at room temperature in the presence of poly(acrylic acid)(PAA). The obtained products were characterized by XRD, IR and SEM. It was revealed that with increasing PAA amount, the crystal polymorph of CaCO 3 particles varied gradually from pure calcite through a mixture of calcite and vaterite to pure vaterite, and the particle size decreased generally. It was proposed that in solid-state reaction, PAA induced the formation of vaterite and the phase transformation from vaterite to calcite was prevented completely due to the absence of H 2O, resulting in the formation of pure vaterite particles.展开更多
文摘Calcium carbonate, the main component of lime, has been widely used in industry due to its stability and economy. Calcium carbonate has three types of crystalline polymorphism, calcite, aragonite and vaterite, each with different properties. Therefore, the control of crystal polymorphism is required for industrial applications. In addition, the control of crystal size and shape is similarly required for different applications. In this study, the effect of SrCO<sub>3</sub> on the size control of fine aragonite-type calcium carbonate crystals by uniform urea precipitation and the effect of SrCO<sub>3</sub> addition was investigated by adding solid strontium carbonate and dissolved strontium carbonate. The addition of solid strontium carbonate affected the crystal polymorphism and size of the calcium carbonate produced, depending on the properties of the solid particles and the amount of SrCO<sub>3</sub> added. Experiments on the addition of dissolved SrCO<sub>3</sub> showed that the supersaturation formation rate could be controlled to control the crystal polymorphism.
文摘Submicrometer-sized, spherical vaterite particles were synthesized by solid-state reaction at room temperature in the presence of poly(acrylic acid)(PAA). The obtained products were characterized by XRD, IR and SEM. It was revealed that with increasing PAA amount, the crystal polymorph of CaCO 3 particles varied gradually from pure calcite through a mixture of calcite and vaterite to pure vaterite, and the particle size decreased generally. It was proposed that in solid-state reaction, PAA induced the formation of vaterite and the phase transformation from vaterite to calcite was prevented completely due to the absence of H 2O, resulting in the formation of pure vaterite particles.
